Fungicide for protecting wood

ABSTRACT

A fungicide for protecting wood comprising an aqueous solution of an alkali metal hydroxide, a metal hydroxide forming hydroxo anions, and an alkali metal salt of ammonium salt of N-nitroso-Ncyclohexylhydroxylamine, and a process for protecting wood against fungus attack by treatment with this fungicide.

Unite Raff et al.

FUNGICIDE FOR PROTECTING WOOD Inventors: Paul Raff, Ludwigshafen; Wolfgang Reutlier, Heidelberg; Harro Petersen, Frankenthal; Ernst-Heinrich Pommer, Limburgerhof, all of Germany Assignee: Badische Anilin- 8: Soda-Fabrik Aktiengesellschait, Ludwigshafen/R- hine, Land Rhineland-Pfatz, Germany Filed: Dec. 9-, 1969 Appl. No.: 883,639

U.S. Cl. ..424/l54, 424/157, 424/325, 424/167 Int. Cl. ..A01n 11/00 Field of Search ..424/l57, 154, 325

[ 51 Apr. 3, 1973 [56] References Cited UNITED STATES PATENTS 2,954,314 9/1960 Metzger et al ..424/32S OTHER PUBLICATIONS Chem. Abstracts, Vol. 43 (1949) p. 352f.

Gregory, Uses & Applications of Chemicals & Related Materials 1939, p. 540.

Primary ExaminerAlbert T. Meyers Assistant Examiner-Vincent D. Turner Att0rneyJ0hnst0n, Root, OKeeffe, Keil, Thompson and Shurtleff [57] ABSTRACT A fungicide for protecting wood comprising an aqueous solution of an alkali metal hydroxide, a metal hydroxide forming hydroxo anions, and an alkali metal salt of ammonium salt of N-nitroso-N-cyclohexylhydroxylamine, and a process for protecting wood against fungus attack by treatment with this fungicide.

6 Claims, No Drawings FUNGICIDE FOR PROTECTING WOOD The invention relates to a fungicide which is suitable for protecting wood.

It is known to protect wood against fungus attack by treating the wood with numerous inorganic or organic compounds as the wood may otherwise be quickly destroyed. However, many of these compounds are washed out or evaporate out of the wood after a'certain length of time. It is also known that the alkali metal salts of N-nitroso-N-cyclohexylhydroxylamine are funsolution of the fungicide to be completely clear; the ingredients of the solution need only be substantially dissolved. A small undissolved residue possibly originating from impurities does not impair the fungicidal action. The term alkali metal hydroxide is taken to mean sodium hydroxide and potassium hydroxide. The term alkali metal salts of N-nitroso-N-cyclohexylhydroxylamine is taken to mean its sodium salts and potassium salts. Single compounds or mixtures thereof may, of course, be replaced by substances which in solution give the corresponding compounds. For instance, an alkali metal salt of N-nitrosohydroxylamine may be replaced by a mixture of N-nitrosohydroxylamine and an alkali metal hydroxide, or the mixture of an alkali metal hydroxide and aluminum hydroxide may be replaced by alkali metal aluminate or by an alkali metal hydroxide and a water-soluble aluminum compound, especially an aluminum salt. The same applies, mutatis mutandis, for the replacement of the other metal hydroxides by the corresponding water-soluble metal compounds, particularly metal salts. The wood may be treated with the fungicide by either impregnating (with or without the application of pressure), spraying or coating with the solution the wood material to be protected and by subsequently drying the wood. During drying, the sparingly soluble metal salt of N-nitrosocyclohexylhydroxylamine is formed, by the action of the natural carbon dioxide content of the air and by the action of the natural acids in the wood, from the soluble alkali metal salts or ammonium salts of N-nitrosocyclohexyl-hydroxylamine and from the alkali metal hydroxo salts, thus providing the wood with lastingprotection against fungus attack. instead of employing natural carbon dioxide, it is also possible to treat the impregnated wood with carbon dioxide or other inorganic or organic acids, e.g. dilute sulfuric acid or acetic acid, or with acid-reacting salts, e.g. ammonium chloride. It is further possible to add the fungicide to a binder for wood-base materials, e.g. to a wood glue for the manufacture of chipboard, protecting in this way the finished chipboard against fungus attack. For this purpose, the fungicide as such, or its individual components separately, may be added to the wood glue either during or after its manufacture.

Generally, alkali metal aluminate and the alkali metal salt or ammonium salt of N-nitrosocyclohexylhydroxylamine are used in stoichiometric amounts (molar ratio 1 3) for the production of the fungicide. However, it is also possible to use different amounts. When manufacturing the fungicide, about 1 to 50 parts by weight of alkali metalhydroxide, 1 to 50 parts by weight of metal hydroxide and l to 100 parts by weight of water may be used per part by weight of the alkali metal salt or ammonium salt of N-nitrosocyclohexylhydroxylamine.

The amount of fungicide necessary for coating the wood (dry substance) may be from to 1,250 g/m particularly 250 g/m. As it is desirable when impregnating the wood to achieve complete penetration, a very large excess of fungicide solution must always be used.

It is important for the storage stability of the fungicide that the pH should be adjusted to between 9 and 12, preferably 1 l.

The solutions may for example be prepared as follows:

Aluminum sulfate is dissolved in water in an apparatus equipped with a stirrer; alkali metal hydroxide is then added in at least such an amount necessary to form the aluminate. The alkali metal salt or ammonium salt of N-nitrosocyclohexylhydroxylamine is then introduced into this solution while stirring. The solution is subsequently adjusted with an acid or a base to the desired pH.

The parts in the following Examples are parts by weight.

EXAMPLE 1 Preparation of a Wood Glue Five hundred eighty-eight parts of phenol, 962 parts of 39 percent formaldehyde and 94 parts of water are placed, while stirring, into a glass flask. One half of 525 parts of 50 percent by weight caustic potash solution, in which 22.5 parts of aluminum hydroxide has been dissolved, is carefully metered in. After each addition, the reaction is awaited and the reaction mixture is, if necessary, cooled. Condensation is carried out for minutes at 60 to 65 C; the remainder of the caustic potash solution is then carefully added. Condensation is continued by heating to boiling temperature until the glue has a viscosity of to seconds (DIN beaker 4). The mixture is cooled to 25 to 30 C, and 232 parts of 39 percent formaldehyde and parts of the potassium salt of N-nitrosocyclohexyl-hydroxylamine are added to it. Preparation of a 5 Percent Fungicide Solution One hundred ninety-eight ml of 2-N caustic soda solution is added to 30.4 parts of Al,(S0,) 1811 0 which has been dissolved in 400 parts of water. While stirring, 55.5 parts of the potassium salt of N- nitrosocyclohexylhydroxylamine is dissolved in this solution; the pH is adjusted to 10.5 by adding ml of N/ 10 H 80 and the solution is made up to 1,000 parts with water. Fungicide solutions having a lower active ingredient content (0.2; 0.5; 1 and 2 percent by weight solutions) may be prepared similarly. Preparation of a 2 Percent Fungicide Solution Twenty ml of S-N caustic soda solution is added to 1.6 parts of ZnCl, dissolved in 10 parts of water. While stirring, 2 parts of the sodium salt (98%) of N-nitrosocyclohexylhydroxylamine is dissolved in this solution and the whole made up to 100 parts with water. Preparation of a 2 Percent Fungicide Solution Twenty-five ml of S-N caustic soda solution is added to 1.4 parts of SnCl,.2H,O dissolved in 10 parts of water. While stirring, 2 parts of the sodium salt (98%) of N-nitrosocyclohexylhydroxylamine is dissolved in this solution and the whole made up to 1100 parts with water. Preparation of a 1 Percent Fungicide Solution 34.5 ml of -N caustic soda solution is added to 2.25 parts of Pb (CH COO) 31-1 0 dissolved in parts of water. While stirring, 1 part of the sodium salt (98%) of N-nitrosocyclohexylhydroxylamine is dissolved in this solution and the whole made up to 100 parts with water. 1

Blocks of spruce and pine wood measuring 50 X 25 X mm were evenly coated with 0.2, 0.5, l and 2 wt.% fungicide solutions and dried for several days in the air. In one series of experiments the specimens were then exposed to attack by the ligniperdous fungus Coniophora cerebella, while the specimens for a second series of experiments were placed, before exposure to the fungus, for three days in running tap water to test the stability of the fungicide impregnation. The experiments on resistance to fungus attack were carried out in glass dishes (diameter 15 cm; height 3 cm), the specimens being placed upon a malt nutrient agar covered with the fungus used for test purposes and being exposed at about 22 C to the fungus attack for a period of 12 weeks.

Fungus used for purpose of the test: Coniophora cerebella %age Specimen/ active extent of fungus extent of fungus type ingredient development on development on the the in the specimens after specimens after the the solution number of weeks number of weeks indicated indicated 3 days in water 4 8 l2 4 8 12 spruce 0.2 0 0 l l 2 2 pine 0.2 0 0 l l l l spruce 0.5 0 0 0 0 1 0 0 pine 0.5 0 0 0 0 0 0 spruce 1.0 0 0 0 0 g 0 0 pine 1.0 0 0 0 0 0 0 spruce 2.0 0 0 0 0 0 0 pine 2. 0 0 0 0 0 0 spruce untreated 3 3 3 3 3 3 pine untreated 3 3 3 3 3 3 O no fungus growth on the specimen; 1 3 slight to complete cover of the specimen with fungus mycelium.

EXAMPLE 2 1 Four hundred sixty ml of 2-N caustic soda solution is added to 67 parts of Al,(SO .18H,O dissolved in 1,800 parts of water. While stirring, 50.8 parts of the sodium salt (98%) of N-nitrosocyclohexylhydroxylamine is dissolved in this solution and the whole made up to 2,500 parts with water. Fungicide solutions having a lower content of active ingredients (0.2; 0.5; 1 and 2 percent by weight solutions) may be prepared similarly.

Blocks of spruce and pine wood measuring 50 X x 15 mm were freed in vacuo in an autoclave of the air in them and were impregnated at 10 atmospheres of nitrogen with a 2 wt.%, 1 wt.%, 0.5 wt.% and 0.2 wt.% aqueous solution of the sodium salt of N-nitrosocyclohexylhydroxylamine containing a somewhat more than stoichiometric amount of sodium aluminate. Some of the blocks were dried in the air, some were treated for 30 minutes in an autoclave at 10 atmospheres of CO, and the remainder treated for 30 minutes in an autoclave at 10 atmospheres of nitrogen with dilute sulfuric acid.

Fungus used for purposes of the test: Coniophora cerebella Spruce lzage wood active extent of the extent of the specimen] ingredient fungus development fungus development type of in the on the specimens on the specimens treatment of solution after the number after the number of weeks indicated 3 days in water 4 8 of weeks indicated 4 8 12 12 a) only air drying 0.2 0 0'0 0 0 0 b) autoclave 10 atm. CO, 0.2 0 0 0 0 0 0 c) autoclave dilute 14,80. 0.2 0 0 0 0 0 0 a) 0.5 0 0 0 0 0 0 b) 0.5 0 0 0 0 0 0 c) 0.5 0 0 0 0 0 O a) 1.0 0 0 0 0 0 0 b) 1.0 0 0 0 0 0 0 c) 1.0 0 o 0 0 0 0 a) 2.0 0 0 0 0 0 0 b) 2.0 O 0 0 0 O 0 c) 2.0 0 0 0 0 0 0 a) untreated 3 3 3 3 3 3 b) untreated 3 3 3 3 3 3 c) untreated 3 3 3 3 3 3 0 no fungus growth on the specimen; 1 3 slight to complete cover of the specimen with fungus mycelium.

We claim:

1. A process for protecting wood against attack by the fungus Coniophora cerebella which comprises coating or impregnating wood with a fungicidally effective amount of an aqueous solution of (I) (a) sodium or potassium aluminate or (b) a mixture of sodium or potassium hydroxide and the hydroxide of aluminum, zinc, chromium, lead or tin and (II) the sodium, potassium or ammonium salt of N-nitroso-N-cyclohexylhydroxylamine in proportions by weight of l-50 parts of (l) per part of (II) and l-l00 parts of water per part of (II) and forming in the coated or impregnated wood the sparingly water soluble salt of N-nitrosocyclohexylhydroxylamine and aluminum, zinc, chromium, lead or tin.

2. A process as claimed in claim 1, (I) being the mixture (b) embodying aluminum hydroxide.

3. A process as claimed in claim 1 wherein (l) is sodium aluminate.

4. A process as claimed in claim 1 wherein said sparingly water soluble salt is formed by drying the coated or impregnated wood in the atmosphere to effect the sparingly water soluble salt formation by the action of carbon dioxide of the atmosphere and the action of natural acids in the wood.

5. A process as claimed in claim 1 wherein said sparingly water soluble salt is formed by placing the coated or impregnated wood in an atmosphere of carbon dioxide gas.

6. A process as claimed in claim 1 wherein said sparingly water soluble salt is formed by impregnating the coated or impregnated wood with dilute sulfuric acid, acetic acid or ammonium chloride solution in an amount sufficient to cause said sparingly water soluble 5 salt to form. 

2. A process as claimed in claim 1, (I) being the mixture (b) embodying aluminum hydroxide.
 3. A process as claimed in claim 1 wherein (I) is sodium aluminate.
 4. A process as claimed in claim 1 wherein said sparingly water soluble salt is formed by drying the coated or impregnated wood in the atmosphere to effect the sparingly water soluble salt formation by the action of carbon dioxide of the atmosphere and the action of natural acids in the wood.
 5. A process as claimed in claim 1 wherein said sparingly water soluble salt is formed by placing the coated or impregnated wood in an atmosphere of carbon dioxide gas.
 6. A process as claimed in claim 1 wherein said sparingly water soluble salt is formed by impregnating the coated or impregnated wood with dilute sulfuric acid, acetic acid or ammonium chloride solution in an amount sufficient to cause said sparingly water soluble salt to form. 